Some anatomical characteristics of stomata in four bread wheat cultivarsunder water stress influence

Abstract

A field experiment was done at the second agricultural experiment station of the College of Agriculture - Al-Muthanna University, during the agricultural season of 2022-2023. The objective of the study was to investigate the physiological response of different bread wheat varieties to the impact of partial irrigation.

 The study employed a randomized complete block design (R.C.B.D) with split plots arrangement and three replications. The main plots consisted of different levels of irrigation deficiency, denoted as D1 (control), D2 (tillering stage), D3 (elongation stage), and D4 (booting stage). The secondary plots included different cultivars, coded as V1 (Mawadah), V2 (Bohuth22), V3 (Baraka), and V4 (Ibaa99).

The statistical analysis yielded considerable disparities among the stages of water stress. The D2 treatment demonstrated superior results in terms of stomatal length on the upper surface (3.720 μm) and the width of stomatal opening on the upper surface (1.300 μm). Following this, the D4 treatment exhibited exceptional performance in terms of stomatal density on the upper surface (147.0 stomata mm^-2) and the width of the aperture on the lower surface (2.880 μm).

 Regarding the cultivars, Bohuth22 demonstrated superior performance in various anatomical characteristics, including the length and opening of the stomata on the upper surface, as well as the length, width, and opening width of the stomata on the lower surface (measuring 3,760, 4,200, 3,540, 2,800, and 1,340 μm, respectively). On the other hand, the cultivar Mawadah exhibited higher density of stomas. The lower surface had a stomatal density of 115.9 stomata mm^-2, while the variety Ibaa99 demonstrated a higher stomatal density of 136.7 stomata mm^-2 on the upper surface.

Regarding the observed overlap, a notable impact was observed across the majority of features, as evidenced by the superior performance of treatment D1V1 in terms of stomatal density on the lower surface (134.8 stomata mm^-2), while the combination D2V1 exhibited superiority in stomatal density on the lower surface (133.3 stomata mm^-2). The treatment D4V2 exhibited a significant increase in stomata density (4.240 stomata mm^-2) and stomata width (127.4 μm) on the lower surface. Conversely, the combination D4V3 demonstrated superior stomata length (4.480 μm) on the lower surface. Additionally, the treatment D4V4 displayed superiority in stomata density (167.4 stomata mm^-2) and stomata length (4.560 μm) on the upper surface, as well as stomata density (125.2 stomata mm^-2) on the lower surface.

Based on the aforementioned information, it can be inferred that water stress exerts a detrimental influence on physiological characteristics. This phenomenon is seen as a plant's adaptive response to withstand stress by diminishing transpiration.